Yongjie Cheng

Passively Q-switched Nd:YAlO 3 nanosecond laser using MoS 2 as saturable absorber

We report on the first passively Q-switched Nd:YAlO₃ laser at ~1079.5 nm using MoS₂ as saturable absorber. The MoS₂ saturable absorber is fabricated by transferring the liquid-phase-exfoliated MoS₂ nanosheets onto a BK7 glass substrate. By inserting the glass MoS₂ saturable absorber into a plano-concave Nd:YAlO₃ laser cavity, we obtain a stable Q-switched laser operation with a maximum average output power of 0.26 W corresponding to a pulse repetition rate of 232.5 kHz, a pulse width of 227 ns and a pulse energy of about 1.11 μJ. The results experimentally confirm the promising application of the new kind of 2D material, few-layer MoS₂, in solid state lasers.

Orange-light passively Q-switched Pr^3+-doped all-fiber lasers with transition-metal dichalcogenide saturable absorbers

We experimentally demonstrated compact orange-light passively Q-switched praseodymium (Pr3+)-doped all-fiber lasers utilizing two-dimensional (2D) transition-metal dichalcogenides (TMDs, WS2 and MoS2) as saturable absorbers (SAs). The filmy TMDs SAs are fabricated by evaporating the composite of TMDs nanosheets and polyvinyl alcohol (PVA), and then inserted into an orange-light Pr3+-doped fiber laser cavity, which is designed by coating dielectric mirrors on fiber ends. Stable passively Q-switched orange lasers at 604 nm are successfully achieved. The passive Q-switching generated the short pulse duration of 435 ns and 602 ns, as well as the tunable repetition rate in the range of 67.3 ~132.2 kHz and 50.8 ~118.4 kHz, respectively. This is, to the best of our knowledge, the shortest-wavelength operation of 2D-material-based pulsed fiber lasers.

Efficient and Compact Diode-Pumped Nd:YAG Lasers at 1073 and 1078 nm

We report on the efficient diode-pumped continuous-wave laser operation of a Nd:YAG crystal at several wavelengths by using a simple and compact two-mirror laser cavity and an undoped YAG thin plate acting as a Fabry-Pérot (F-P) etalon. We thus obtain a high-power single-wavelength laser operation at about 1073 nm with a maximum output power of 5.58 W and a laser slope efficiency of about 36.6%, with respect to absorbed pump power, which is believed to be the highest output power ever obtained with Nd:YAG at 1073 nm. We also achieve dual-wavelength laser operation at 1064 and 1078 nm, with a maximum output power of 1.57 W, and triwavelength laser operation at 1061, 1064, and 1078 nm, with a maximum output power of 2.16 W. This is the first demonstration, to the best of our knowledge, of a diode-pumped Nd:YAG laser at 1078 nm.

Compact Passive Q-Switching Pr 3+ -Doped ZBLAN Fiber Laser With Black Phosphorus-Based Saturable Absorber

In this paper, a compact passively Q-switched praseodymium (Pr3+)-doped fiber laser at the wavelength of 635 nm with black phosphorus (BP) saturable absorber (SA) was first investigated. BP nanoflakes were manufactured by the liquid-phase-exfoliation method and then embedded into polyvinyl-alcohol (PVA) film for the experimental usage and a fiber pigtail mirror (FPM, by coating dielectric film onto the fiber-end face) was applied to realize a compact Pr3+-doped red fiber laser. By transferring a block of the BP-PVA thin film onto the FPM and then incorporating into the compact Pr3+-doped fiber laser, the Q-switched operation at 635 nm was achieved. The pulse-repetition rate of the visible-wavelength Q-switched fiber laser can be widely tuned from 108.8 to 409.8 kHz and the shortest pulse duration of this laser is 383 ns. These results reveal that the BP is an available SA for red-light lasers.

Passive Q-Switching of a Diode-Pumped Pr:LiYF 4 Visible Laser Using WS 2 as Saturable Absorber

Q-switched laser operation of a blue-diode-pumped Pr:LiYF4 laser is demonstrated at 640 nm for the first time by using a tungsten disulfide (WS2) nanosheet material as a saturable absorber. Stable laser pulses of 630 ns are obtained with a pulse repetition rate of 88 kHz, a pulse energy of about 0.24

Nanosecond pulse generation in a passively Q-switched Nd:GGG laser at 1331 nm by CVD graphene saturable absorber

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Emission properties and CW laser operation of Pr:YLF in the 910 nm spectral range

, and an average output power of 21.5 mW. This paper broadens the application of WS2-like 2-D nanosheet saturable absorbers from the near- and mid-infrared to the visible domain.

Passively

We report on a nanosecond pulse generation in a diode end-pumped passively Q-switched Nd:GGG laser at the low-gain transition line of 1331 nm. A three-layer CVD graphene thin film was transferred from Cu foil to a BK7 glass substrate for the use of saturable absorber. A stable Q-switching laser operation was obtained with maximum average output power of 0.69 W and slope efficiency of about 11.0% with respect to the absorbed pump power. The shortest pulse duration and the maximum repetition rate of the pulse trains were registered to be 556 ns and 166.7 kHz with corresponding maximum pulse energy 4.14 μJ and pulse peak power 7.45 W. This is the first demonstration of CVD-graphene-based Q-switched laser operation at 1.3 μm, to the best of our knowledge.

Q

The polarized emission spectra for the 3P0→1G4 emission transition of the Pr3+ ion around 910 nm in the Pr3+:LiYF4 (Pr:YLF) laser crystal were registered and calibrated in unit of cross sections for the first time. Continuous-wave (CW) laser operation is demonstrated at 915 nm in π polarization by pumping the crystal with an optically pumped semiconductor laser (OPSL) at 479.2 nm. An output power of 218 mW is thus obtained with a laser slope efficiency of about 24% for an output coupler (OC) transmission of 1.9%. CW laser operation is also demonstrated at 907 nm in σ polarization by using a thin plate oriented at Brewster angle. An output power of about 89 mW with a slope efficiency of about 10% is then obtained for an OC transmission of 0.8%.The round-trip cavity losses are estimated for different experimental cavity configurations to be about 1% and the typical beam quality M2 factors measured in the transverse x and y directions are found equal to about 1.07 and 1.04, respectively. Finally, we also report on a double laser wavelength operation by using an OC with a transmission of about 0.05%, such effect resulting from joint-etalon effects inside the cavity.

-Switched Red Pr 3+ -Doped Fiber Laser With Graphene-Oxide Saturable Absorber

In this letter, a compact Q-switched red (635.7 nm) praseodymium (Pr3+)-doped fluorozirconate fiber laser using graphene-oxide (GO) as a saturable absorber (SA) is demonstrated experimentally. Furthermore, a silica fiber end coated with a dielectric film was employed to construct the compact resonator. The laser possesses a wide range of pulse repetition rate from 64.1 to 195.3 kHz and the minimum pulse duration of 554 ns. This is the first reported passively Q-switched laser, to the best of our knowledge, at visible region with a GO SA. The experimental results show that the GO can be a promising SA for visible pulsed lasers.